I've said this before: there are no "low leverage" relievers in a modern pen. You're using 3, 4 maybe 5 relievers every night. Most professional baseball games are close, it's just the nature of the game. EVERYone in the pen is going to be in a position to win or lose games, and not just as an oddity. A manager can't just use 3 or 4 guys for 4 innings every close game.
I'm not a Rocco apologist, by any means, but he needs an inning of performance, minimum, when he puts a guy into a game in the middle innings, no matter the guy. And He doesn't have the luxury of having another guy already warmed and ready when a Cano starts an inning. Cano needs to perform.
The problem really is not Rocco leaving Cano in too long. The problem is not providing Rocco with enough good options. Blame Cano. Or Falvine.